Differential Diagnosis: Apraxia or Phonological Disorder

Sue Caspari, M.A.,CCC-SLP

May 4, 2009

Question

A new child was recently placed on my caseload. She is in 2nd grade and highly unintelligible. Although there is a family history of hearing loss (not immediate family), hearing loss was ruled out for this child. There are most likely cognitive issues and

Answer

My first thought, given the family history of hearing loss, is to confirm there is no hearing loss - depending on how and when the hearing loss was initially ruled out, this is something you may want to confirm (get a second opinion on). Certainly omitting consonants and distorting vowels are consistent with hearing loss, and so it may be prudent to recommend an audiological evaluation just to confirm that the information you have been given is accurate.

If you are confident that there is no hearing loss, and if you haven't done so already, a comprehensive speech and language assessment will help guide your treatment decisions. You will want to try to differentially diagnose her speech disorder - for example, is it phonologically based, or motor based, or perhaps both. Without a differential diagnosis, treatment decisions cannot be made, as treatment for motor speech disorders are markedly different than treatment for phonological disorders. Errors that you describe, such as initial consonant deletion, and vowel errors can point toward motor planning and programming difficulties (apraxia). Errors that you describe such as final consonant deletion and syllable reduction could point towards a phonological disorder. She may have one or the other, or she may have both. Different speech disorders can co-occur. So, if she exhibits characteristics of more than one disorder, it will be important to try to determine the relative contribution of each disorder to her overall speech disorder so that treatment can be geared to the primary contributing disorder.

Additionally, you will want to fully assess her language skills, especially in light of the earlier referral to "rule out aphasia", in order to determine any language-based contributing factors, as well as to get clues that may relate to her speech disorder (for example, apraxia of speech typically occurs with receptive language skills stronger than expressive language skills).

Due to the severity of her speech disorder (only having two intelligible verbal words), you will also want, rather soon, to assess her functional use of language in all modalities (sign, picture point, gesture, etc.) to determine if there is an augmentative communication system that could be implemented to help her functionally communicate despite her profound speech disorder.

It sounds like she is a complicated case, and if you suspect that she may have a motor speech disorder (apraxia of speech or dysarthria) and you do not feel that you are equipped to make a differential diagnosis, you are encouraged by the American Speech Language and Hearing Association (ASHA) to refer her to a speech-language pathologist with extra training and knowledge in diagnosing and treating children with motor speech disorders (see the ASHA 2007 position statement and technical report on childhood apraxia of speech at www.asha.org/docs/pdf/PS2007-00277.pdf, and www.asha.org/docs/pdf/TR2007-00278.pdf. A list of speech language pathologists who feel they are equipped to make such a diagnosis can be found at the Childhood Apraxia of Speech Association of North America (CASANA) website at www.apraxia-kids.org. The apraxia-kids website also has a wealth of information on their website regarding diagnosis and treatment of motor speech disorders that you may find beneficial, including a chart comparing phonological disorders, apraxia of speech and dysarthria that you may want to look at.

Once you have been able to fully assess her speech and language skills, and obtain an understanding of her cognitive status, you will be ready to determine a treatment program that is specific to her disorder(s).

Sue Caspari, M.A., CCC/SLP, is a speech-language pathologist working in private practice in the Philadelphia area. She has more than 10 years experience working with children and adults with neurogenic speech and language disorders in early intervention, and hospital settings, including the Mayo Clinic. In her current practice, she works primarily with, and as a consultant and advocate for, children with severe speech production disorders. She has advanced knowledge and experience in the areas of childhood apraxia of speech (CAS) and alternative and augmentative communication. Sue conducts workshops on CAS, and speaks on apraxia of speech at national conferences such as the American Speech-Language-Hearing Association's (ASHA) annual meeting. In addition to her clinical practice, Sue works as an educational software development and marketing consultant. Sue is an associate member of the Academy of Neurologic Communication Disorders and Sciences and a member of ASHA's Neurophysiology and Neurogenic Speech and Language Disorders Special Interest Division; is licensed in the state of Pennsylvania; and holds a Pennsylvania teaching certificate for the speech and hearing impaired.